The invention described herein relates to a method for producing carrier-free .sup.68 Ga in ionic form and more particularly to a method for the rapid separation of .sup.68 Ga from .sup.68 Ge based on the volatilization of chloro-germanium compounds from strong aqueous HCl. It is a result of contract W-7405-Eng-36 with the Department of Energy.
The short-lived radioisotope .sup.68 Ga (half-life of 68 minutes) is useful in a variety of biomedical applications, e.g., in bone imaging and soft-tissue tumor imaging.
Gallium-68 is obtained as a daughter of 288-day .sup.68 Ge. It is known that the separation of .sup.68 Ge and .sup.68 Ga can be accomplished by extraction and adsorption techniques. Thus, for example, .sup.68 Ga (not carrier free) may be extracted with acetyl acetone from acidic solution and then back extracted into 0.1 M HCl. Alternatively, .sup.68 Ge (not carrier free) may be extracted from HCl solution (.about.9 M) by carbon tetrachloride, with the .sup.68 Ga remaining almost entirely in the HCl solution. A commercially available .sup.68 Ga generator makes use of carrier-free .sup.68 Ge which is strongly adsorbed on aluminum oxide. The .sup.68 Ga is eluted with a neutral solution of 0.005 M EDTA. The .sup.68 Ga is obtained in the form of a Ga-EDTA complex.
For many medical applications, it is necessary to prepare the gallium in the ionic form. To accomplish this, the .sup.68 Ga-EDTA chelate is usually destroyed by digestion with concentrated HCl after the addition of gallium carrier. The .sup.68 Ga is separated in ionic form by ion exchange or extraction. Because of the rapid decay of the .sup.68 Ga, only a 30% yield or less can normally be expected. Moreover, heretofore at least, Ga/Ge separation factors in the range of about 10.sup.4 to 10.sup.5 have been achieved. It would be quite advantageous to achieve higher separation factors.
Accordingly, it is an object of this invention to provide a procedure for separating ionic .sup.68 Ga from .sup.68 Ge.
Another object is to provide a rapid method for separating carrier-free .sup.68 Ga from carrier-free .sup.68 Ge.
Yet another object is to provide a method for separating .sup.68 Ga from .sup.68 Ge wherein the separation factor exceeds 10.sup.5.
Other objects, advantages, and novel features of the invention will become apparent to those skilled in the art upon examination of the following detailed description of a preferred embodiment of the invention and the accompanying drawings.